I recently saw an article about how tonight at 23:31:30 GMT the unix clock used in any unix system will reach 1234567890 due to it being a 32 bit interger clock, however I know that OS X Leopard was made 64 bit dunno if this means the clock was adjusted as well.
Here is the full article http://technology.timesonline.co.uk/tol/news/tech_and_web/article5727189.ece
Here is the full article http://technology.timesonline.co.uk/tol/news/tech_and_web/article5727189.ece